I searched the web on this topic and got plenty of suggestions from every one (including other stackoverflow threads).
Finally, I thought implement as shown exactly here.
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.repeater.onitemcommand(VS.71).aspx
Still frustrated.
My repeater is available in a user control and I added the user control as a web part to an existing webpartzone. I could see all rows in the repeater (along with buttons). Once I click the (any) button, it loses all the rows and itemcommand never fires.
I am using ASP.NET 4.0
Can anyone help me on this.